How to reclaim space after getting the Windows 10 Fall Creators Update

If you're running low on space after getting the Windows 10 Fall Creators Update, use this guide to delete the previous version to reclaim storage.
During the installation of the Fall Creators Update, Windows 10 makes a backup of the current setup that can be used to restore the previous configuration in case of problems during and after the upgrade.
The only caveat is that even after the Windows 10 Fall Creators Update was successfully installed, and it's working without a glitch, the copy of the previous version stored in the Windows.old folder is still around on your drive — wasting gigabytes of space that can be used by more important files.
Although this might not be an issue for devices with large hard drives, if you have a laptop or tablet with limited storage, you can reclaim that storage space (and more).